Extrasolar Gas Giants?

[Daniel O]

So far the only extrasolar planets we have found are all gas giants.

My question is WHY do they think they are all gas giants? Most of them are very close to their star. Wouldn't the solar winds blow the atmostphere of the gas giant away?

Is there any reason that giant TERRESTRIAL planets cannot exist? We do not have them in out solar system, but does that mean they cannot form?

Just curious, thanks.

Dan,

 

[Robert L]

Gas giants orbitting close to the parent star ar easiet to detect. An eath-like planet orbitting a star in a 1-year orbital period would be hard to detect. That is what Kepler telescope is supposed to help do.

 

[Anonymous Viking]

Gas giants are easy to find because they weigh a lot.

Swing a toddler or a shotput on a rope and you'll be pulled off center a little, and trace a circle. Get a bigger toddler and you'll find yourself making a bigger circle. Try it with an adult and it may be unclear who is swinging whom.

Stars with large planets wobble because as they pull on the planet the planet pulls on them too. By watching for redshifting from that wobble (the star appears to be coming towards us and going back periodically) we can tell which stars have something really heavy in orbit around them.

It's much easier to see a wobble if a star has a morbidly obese toddler and it is holding it on a short rope. It's like asking why a fisherman with five inch trawler netting catches nothing under five inches; they're fairly sure minnows exist but scientists don't have the right tools for the job.

I've seen plans to build a really huge telescope with complicated optics for sorting out the glare of the parent star from small terrestrial planets but as far as I know there are no active projects.

 

[tick tock]

you asked four questions.

1) the planets detected would have to be massive to cause the back and forth wobble detected, knowing the stars mass, the planets mass can be closely estimated.

2) for most of the 20th century planetary cosmologists have suggested that the formation of a gas giant nearer a star than "The Frost Line" would be impossible. After telling the world that "babies are impossible" the theorists were presented with a bouncing baby boy. Time for a new theory. Now, we think "hot Jupiters formed outside the frost line and "migrated in". Could be they were old and thought they were going to Florida.

4) no reason giant terrestrial planets cannot exist... up to a point. A better question is: Why do Terrestrial Planets exist AT ALL?

5) When you only have one example of a process, its HARD to come up with a theory that is general. The Solar System is a specific example of stellar planetary system evolution... and now we know it's not the norm. Give us a few more years and we might figure out why.

6) what happened to 3)?

 

[tick tock]

you asked four questions.

1) the planets detected would have to be massive to cause the back and forth wobble detected, knowing the stars mass, the planets mass can be closely estimated.

2) for most of the 20th century planetary cosmologists have suggested that the formation of a gas giant nearer a star than "The Frost Line" would be impossible. After telling the world that "babies are impossible" the theorists were presented with a bouncing baby boy. Time for a new theory. Now, we think "hot Jupiters formed outside the frost line and "migrated in". Could be they were old and thought they were going to Florida.

4) no reason giant terrestrial planets cannot exist... up to a point. A better question is: Why do Terrestrial Planets exist AT ALL?

5) When you only have one example of a process, its HARD to come up with a theory that is general. The Solar System is a specific example of stellar planetary system evolution... and now we know it's not the norm. Give us a few more years and we might figure out why.

6) what happened to 3)?